1. Field of the Invention
The present invention relates to a piezoelectric/electrostrictive device which has at least a stacked type piezoelectric/electrostrictive element formed by a film formation method on a ceramic substrate. The element has a structure in which piezoelectric/electrostrictive layers and electrode layers including piezoelectric/electrostrictive materials are alternately laminated in a comb shape.
2. Description of the Related Art
A piezoelectric/electrostrictive device such as an actuator element or a sensor element using a piezoelectric/electrostrictive layer is produced as follows. A wiring pattern made of a first electrode layer is formed on a ceramic substrate by printing, for example. A piezoelectric/electrostrictive layer is further formed thereon by printing, followed by sintering to fix the layer. After that, a wiring pattern made of another electrode layer is formed (see, for example, Japanese Laid-Open Patent Publication No. 2001-320103).
The piezoelectric/electrostrictive device can be used as an actuator element in which an electric field is applied to the piezoelectric/electrostrictive layer by supplying an electric signal to the wiring pattern so that the piezoelectric/electrostrictive layer is consequently displaced. The device also can be used as a sensor element. In the sensor element, an electric signal generated depending on the pressure applied to the piezoelectric/electrostrictive layer is outputted from the wiring pattern.
In the piezoelectric/electrostrictive device as described above, when the electrode layers and the piezoelectric/electrostrictive layers are alternately formed on the ceramic substrate to form a multilayered piezoelectric/electrostrictive driving section, a part of one electrode layer is protruded outwardly from a portion substantial operating section) which functions as an actual driving section (or a sensing section), because it is necessary to form a connecting terminal on the part of the electrode layer. In this structure, in order to avoid a short circuit between the part of the electrode layer (protruding portion) and another electrode layer, the piezoelectric/electrostrictive layer is also protruded in conformity with the part of the electrode layer.
However, in the above structure, an unnecessary electrostatic capacity is formed by the part of the electrode film, the protruding piezoelectric/electrostrictive layer, and the other electrode film. As a result, a CR time constant concerning supply of an electric signal may be consequently increased (a response rate may be lowered).